À curcumin derivative for organic optoelectronics

An organic material is electroluminescent when it emits light when subjected to electrical excitation. This physical phenomenon is the basis for the design of organic light-emitting diodes (OLEDs), devices that are currently invading the television and smartphone display markets. This article describes the photophysical properties of an organic dye whose structure is derived from curcumin. In a solid matrix, this compound emits near-infrared fluorescence and electroluminescence. Analysis of fluorescence spectra and decays shows the significant contribution of delayed fluorescence emission, which explains the high external quantum yield (around 10% at 720 nm) of a light-emitting diode. This dye falls into the category of so-called 3rd-generation electroluminescent materials. Unlike all other examples of this type of material, the molecule in question also displays the ability to amplify light from a favorable process of stimulated fluorescence emission. This is the first example of an organic dye to combine these two properties. These results pave the way for the realization of both continuous and electrically pumped organic lasers. The latter represents one of the major challenges in the field of organic lasers. This article describes the photophysical properties of the dye under consideration, based on general concepts describing the excited states of organic molecules and the mechanism of delayed fluorescence.